Chait bi lV. 
MECHANICAL STRENGTH OF WEBS AND PHYSICAL POWER 
OF SPIDERS. 
ds 
THE size of orbwebs varies generally with the size of the builders. But 
location, the condition of the wind, and contiguity of other webs have 
much to do in determining the matter. 
The abundance of insect food may be a factor modifying both form 
and size. An example of this was seen 
in the colony of Epeiroids referred to, 
Chapter III., as stretching their 
Soe nets across the water between the 
ie aihey. boat houses at Atlantic City. 
(Fig. 61.) There the flies swarmed 
in such myriads that the difficulty of ob- 
taining food was reduced almost to the 
minimum. As a consequence most of the 
spiders hung in the merest rudiments of 
webs, as shown at Fig. 216. In some cases 
these may haye been the remains of more 
or less perfect snares, which had become 
reduced to remnants by struggles of in- 
sects; but many of them showed no traces of any other architecture than 
that here represented, and I inferred that the spiders had discovered that 
the building of complete orbs was a useless waste of labor and material, 
and had spun no more than the central space. 
A Furrow spider taken from the railings of a bridge, where its space 
was circumscribed by location and by numerous webs of its fellows, when 
placed in a roomy cell spun an orb eleven and a half inches 
long by eight inches wide, hung upon a foundation line sixteen 
inches long. The same aranead, when placed in a glass jar three 
inches wide, wove a small characteristic web, or an apology for one, not 
unlike the rudimentary snare at Fig. 216. Argiope cophinaria often makes 
a very small web, and is quite sure to do so when the arboreal spaces 
surrounding it are straitened. But when domiciled where her lines 
could be carried long distances I have known her to make an orb more 
than two feet in diameter. 
Fic. 216. A rudimentary snare of Epeira. 
Modified 
by Site. 
